1. Field of the Invention
The present invention relates to a cam lock device and fastening system that can be used to connect at least two sheet metal panels, the panels having an improved flange construction, preferably in the assembling of paint spraying booths.
2. Description of the Prior Art
In the sheet metal industry, sheet metal panels can be connected by a variety of methods. But, primarily the method for assembling paint spraying booths has been to use nuts and bolts, which can often mean a very unsatisfactory use of man power. This method, in addition to being not very cost effective, requires that holes be made in the sheet metal panels and this is often not acceptable. In most body shops, automobile service departments and car painting businesses, the paint spraying booths are set-up and torn down on a regular basis. The speed in which this is done is very important, as is the necessity that they be tight enough to seal in the dust and paint vapors. The holes made in the panels for the nuts/bolts is a source of future problems. Also, the introduction of holes into the panels will further require that the panels have perfect alignment, whenever and wherever they are assembled. In the preferred embodiment, that being where the cam lock of the present invention is used to connect together sheet metal panels, the major industrial application is in paint spraying booths. These booths will be found in virtually every automobile dealer service department, auto body shop, automobile paint shop etc.. The prior art has previously addressed the long-felt need for combining together metal panels by less labor intensive methods than nuts and bolts.
U.S. Pat. No. 3,900,931 issued to Lavoillote on Aug. 26, 1975, discloses a releasable panel fastening device. This invention utilizes a key to lock the plates together. In order for the plates to be locked there must be slots in them or else the device will not work. A key is inserted and by turning it the connection will either be tightened or released. Although some labor is saved, this invention would be more suitable to an application which does not require tight sealing such as required with a paint spraying booth.
Athough Peterson does not teach using his pivotal locking device, which is disclosed in U.S. Pat. No. 3,453,925 issued on Jan. 12, 1968, to connect sheet metal panels for paint spraying booths, he does teach of a device that uses a locking lever and which engages a cam bearing plate element. Again, holes are necessary to be made in the material and the invention does entail numerous parts which tend to make it less cost effective.
U.S. Pat. No. 4,145,862 issued to Henry A. Sygnator on Mar. 27, 1979, describes a sheet metal fastening device for securing two work panels together. Again, no reference is made for possible use in paint spraying booths, however a labor saving method is disclosed. In operation, the retainer plates are preferably pre-assembled so that the fastener of the invention can be aligned within an aperture of one of the plates. The plates are then clamped tight when aligned elongated apertures of one of the panels are assembled over the locking region. However, this invention does not teach a method of securing the that would avoid using holes or slots.
U.S. Pat. No. 5,011,356 issued to Miguel C. Fernandez on Apr. 30, 1991, discloses a method of fastening a plurality of overlapped panels. He utilizes a pair of diametrically opposed inclined cam portions. The panels, upon completion of a 90 degree rotation, are disposed in a compressed state. Again this invention requires holes or slots in order for the panels to be attached. This would make it very ineffective for use with paint spraying booths.
U.S. Pat. No. 5,011,355 issued to Inaba Motoshige on Apr. 30, 1991, teaches of a push button type fastener which is releasable by rotation. The fastener requires a stud assembly to be snap-fitted to one panel while a mating socket is similarly fitted to another panel. The stud assembly and the socket are releasably secured to each other merely by the pushing of a stud toward the mating socket, whereby two resilient arms move apart to receive and lock the device. Once again, this device requires apertures in the sheet metal and while it appears to be an improvement over the prior art, it does not appear to overcome the basic problem, which is to avoid having holes in the panels.
U.S. Pat. No. 5,302,039 issued to Bruce Omholt on Apr. 12, 1994, teaches a panel coupler that does not require any holes to the panels to be coupled. The coupler will releasably and adjustably hold two or more panel clamps for coupling together two or more adjoining panels. The outstanding feature of this invention is that more than two panels can be connected by any one coupler device. It does overcome some of the prior art shortcomings, such as holes in the panels, fixed width panel receiving channels which offer very little versatility, and of course heavy, cumbersome devices. This invention can accommodate, without any modifications, three or more panels, and panels of varying thicknesses. The invention can be lightweight, even plastic. The major problem area of the invention is that when the panels are attached, a tight fit between the panels is not possible. Thus, this invention would have difficulty being utilized in an application that involved a paint spraying booth.
U.S. Pat. No. 4,693,629 issued to Robert F. Bruinsma on Sep. 15, 1987, shows a fastener that joins a plurality of panel members together at their corners and will provide a tight, aligned joint between panels. The device can be easily and very quickly disconnected to facilitate the movement of the panels from one place to another. Here, the panels do need to have notches formed within them, such that a part of the device extends into the notches and abuts them in a clamping arrangement as found in much of the prior art. This fastener addresses the long felt need for a fastener which is separate from the panel structure itself, is relative easy to install or replace, requires no special aligning devices, and finally can join several panels. However, it can only connect panels at their corners and therefore is not very functional for use in a paint spraying booth.
The present invention overcomes the foregoing disadvantages of prior panel locking devices by providing a cam lock that can easily be used to couple two or more sheet metal panels yet still be able to accommodate panels of different thicknesses. None of the prior art is seen to be as simple in construction nor as easy to operate as the present invention. The present invention does not require any holes, slots, notches or apertures of any kind in the sheet metal panel in order for it to operate.
None of the above noted patents, taken either singly or in combination, are seen to disclose the specific arrangement of concepts disclosed by the present invention.